1. Technical Field
The present invention relates to a method for fabricating a disk drive system of a hard disk, and more particularly to a method for surface-treating respective structural components of a disk drive system.
2. Background Art
In general, a hard disk apparatus of a rotary actuator type for use with a microcomputer, for example, as shown in U.S. Pat. No. 5,369,538 for Rotary Disk Drive Actuator issued to Moe et al., U.S. Pat. No. 5,363,262 for Magnetic Disk Apparatus And Method For Manufacturing The Same issued to Kawakami, and U.S. Pat. No. 5,404,636 for Method Of Assembling A Disk Drive Actuator issued to Stefansky et al., is constructed with a generally, rectangularly shaped base serving as a frame accommodating a plurality of circular disks coaxially mounted in a stack upon a spindle driven by a motor mounted on the base to provide a plurality of cylindrical base surfaces that serve as a memory into which binary information may be written and read, an actuator mounted upon the base by a pivot such as a threaded fastener to freely rotate about the longitudinal axis of pivot, and a voice coil motor assembly positioned to respond to electrical control signals and thereby arcuately displace a proximal end of the actuator. Actuator arm supports, at its distal end, a plurality of electromagnetic transducers commonly known as read/write actuator heads corresponding to the distinct separate cylindrical base surfaces of disks that serves as memories. Typically, the base surfaces of disk are coated with a magnetically sensitive material that responds to fields created by corresponding ones of actuator heads, to enable the actuator heads to either write bits of information at selected locations along tracks formed on the surface of the disk, or to read information from those tracks. Generally, the disk continuously rotates in a single direction while the voice coil motor assembly acts upon the proximal end of the actuator arm to arcuately displace the proximal arm relative to motor and thereby cause the distal ends of actuator arm to radially position heads along corresponding base surface of disk. A cover is then mounted upon the upper surface of base, to enclose disks, actuator and voice coil motor assembly, and to thereby seal the interior of disk drive in order to protect the environment where disks reside from dust and contaminants. Known tape seals such as one disclosed in U.S. Pat. No. 5,270,887 issued to Compact Disk Drive Head Disk Assembly With Conformable Tape Seal issued to Edwards et al. may be used to provide a substantial airtight seal between the base and cover to thereby maintain a desired clean environment within the disk drive.
Actuator heads "fly" over the corresponding base surfaces of disks, and are normally spaced apart from those surfaces by a low flying height, for example, 4 .mu.m formed by a cushion of air generated by the rapid rotation of the disks. Voice coil motor assembly drives the proximal end of actuator to move heads to a desired information track of disks. Generally, voice coil motor assembly includes a bottom plate, a top plate, magnets and a current coil fixed to the proximal end of the actuator. The current coil is situated between the bottom plate and the magnet with fixed gaps between them. When a control current flows through the coil, the actuator rotates about the longitudinal axis of pivot by an interaction of magnetic fluxes produced individually by the coil and the magnet. As the actuator heads maintain a low flying height over the disk surface, even small dust particles, such as cracked particles created during fabrication of disk drive including voice coil motor assembly, can interfere with the head/disk interface, causing the heads to "crash" or otherwise interfering with the reading/writing of data onto the disk surface.
Accordingly, it has been necessary to keep the air in the disk drive housing relatively free dust particles and other contaminants so as to maintain high performance of the disk drive. Conventional method for fabricating voice coil motor assembly requires all components to be surface treated with a thin nickel coating. For example, the top and bottom plates are individually coated by a well-known nickel plating process, the magnet is coated by either the nickel plating or an electrodeposit coating process, the base and the cover are individually coated by either electrodeposit coating process or chromate conversion treatment. In addition to the surface-treatment of each individual component of the voice coil motor assembly, cleaning, pretreatment, drying and packaging of each individual component arc all necessary prior to the final assembly. Consequently, production cost of the hard disk is increased; moreover, it is difficult to completely eliminate all dust particles generated during the assembling of all respective components of the voice coil motor assembly. If the dust particles are not completely eliminated, the hard disk is then contaminated, and "crash" or "scratch" often occurs in the actuator heads or the disk surface.